Hunter 25 Sails
I had a 1978 Hunter 25 Shoal Draft with both 'hank-on' 110 Jib and a 150 Genoa. The previous answers are substantially correct but your particular wind condition and proposed sailing direction should govern your sail selection. The 110 and a full mainsail will be the learning combination, particularly in winds from 10 knots and above. When you are used to the boat and the wind conditions you should try the 140 in medium light air, say 5-10 knots on a reach. As you gain confidence, again in winds under 10 knots, sheet in the 140 and head up from a reach to close reach, and finally sheet the boom on the main 3-6" below the centerline of the boat and trim the 140 Genoa in progressively tighter until you are just beginning to backwind the main for beating up wind. Obviously you will get a feel for how the boat will be healing more as you sheet in the sails and sail up wind and conversely will see how the sails need to be progressively let out as you sail from a reach to a broad reach and closer to a downwind angle.After you feel comfortable with the 140 and the full mainsail, try the 170 on a light air day, say 4-8 knots. This is predominantly a down wind 'drifter' and is typically not intended to be trimmed in tight to beat to windward.It does have it's place , but each of the jibs or Genoas are intended for a specific wind range. When you are first learning the feel of the boat, it might be appropriate to have more experienced crew to help out. You should have at least one crew member to help you raise or lower the 140, and maybe two crew for the 170 untill you feel more confident, but dangerous is too strong a word if you practice in light air.I loved my 25, had a lot of wonderful times and fond memories with my two sons starting when they were 8 and 10 years old.I hope you enjoy yours as much.